Variability of habitat use by the European eel during its resident yellow eel life stage across the distribution range

• Main Author: Schaal, Ellen
• Format: Other/Unknown Material
• Language: English; Swedish
• Published: SLU/Dept. Of Aquatic Resources 2024
• Subjects: habitat use; otolith; inter-habitat shifters; resident eels; salinity; Anguilla anguilla; European eel
• Online Access: https://stud.epsilon.slu.se/19815/

The European eel (Anguilla anguilla) is a critically endangered species with a complex life history. The eel was previously described as an obligate catadromous fish (which hatch in marine water, spend the majority of their lives in freshwater, and then migrate back to spawn in marine water) but has in later years been reclassified as a facultative catadromous fish. The difference being that a facultative catadromous fish does not always migrate into freshwater. The habitat use of the yellow eel can be classed into freshwater residents, marine residents, brackish residents, and inter-habitat shifters. The aim of this study was to explore and assess the variability of the yellow eel’s habitat use across its distribution range with a focus on habitat salinity. The study was conducted by gathering data from existing articles categorising habitat use based on Sr:Ca ratios in otoliths. After a screening of 99 articles, data analysis was conducted on results from 11 articles covering 10 countries. Of the 1290 sampled eels, 38% were freshwater residents, 26% were marine residents, 14% were brackish residents, 21% were inter-habitat shifters and, 1% were non-classifiable. Sample sizes and proportions of eels in each category varied greatly between countries. Den europeiska ålen (Anguilla anguilla) är en akut hotad art med en komplex livscykel. Ålen var tidigare klassad som en obligatorisk katadrom fisk (som kläcks i marint vatten, spenderar majoriteten av sitt liv i sötvatten och sedan migrerar tillbaka för att para sig i marint vatten) men har på senare tiden omklassificerats till en fakultativ katadrom fisk. Skillnaden är att en fakultativ katadrom fisk inte alltid migrerar till sötvatten. Habitatvalen hos gulålen kan klassas som levande i sötvatten, levande i marint vatten, levande i bräckt vatten eller habitat bytande. Syftet av denna studie är att undersöka och bedöma variationen av habitatval hos ålen genom hela sitt distributionsområde med fokus på val av salthalt. Studien gick ut på att samla data från redan ...